Reduction in sensation of the female genitalia due to excessive consumption of alcohol. This can lead to inadequate physical arousal and/or inability to achieve orgasm. This is the female equivalent of whiskey dick.

That last pint gave Angela the courage she needed to invite Tom back to her place but, alas, left her with a bad enough case of beer muff that she was unable to truly enjoy it.

when you think you heard something spectacular only to find out the next day that it wasnt nearly as good as you thought
similar to beer goggles only using hearing not vision

last night i downloaded the best song when i got home from the club. but i must have had my beer muffs on cause today when i listened to it, i wanted to light my ears on fire and proceed to chip away the charred remains

See also "beer goggles". A certain level of alcohol intoxication renders otherwise attractive people who are annoyingly talkative, less annoying. An ugly annoying person would require both beer goggles and beer muffs. AKA "beer plugs".

She was really annoying, but once I put on my beer muffs, I didn't mind so much.